Method for producing aluminum-containing particles

Abstract

A method for producing particles in which mixed particles are obtained by mixing particles to be treated that include a heavy metal having a specific gravity of 4 or more, an aluminum source, an activator including a halide, and a sintering-preventing agent, the mixed particles are heated and the particles to be treated are calorized by using gaps between sintering-preventing agent portions formed by the sintering-preventing agent to obtain a treated mixture including aluminum-infiltrated particles, and the sintering-preventing agent is removed from the treated mixture to recover the aluminum-infiltrated particles.

Description

[Technical Field]

[0001] The present invention relates to a method for producing aluminum-containing particles. [Background technology]

[0002] Aluminum-containing particles exhibit excellent oxidation resistance at high temperatures and other properties, making them suitable for a variety of applications.

[0003] For example, Reference 1 describes using particles containing an intermetallic compound phase of iron and aluminum as a raw material for thermal spraying and performing atmospheric plasma spraying to form a coating of iron-aluminum intermetallic compound on the surface of stainless steel. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. WO2018 / 116856 [Overview of the project] [Problems that the invention aims to solve]

[0005] The particles in Reference 1 are prepared by calcining a mixed powder containing an iron-aluminum intermetallic compound powder and an iron-containing powder at a high temperature.

[0006] However, according to the present inventors, it has been found that the surface of particles prepared by this method contains regions where aluminum is absent. In particles containing such aluminum-free surface regions, the desired properties may not be exhibited.

[0007] This invention has been made in view of the above background, and aims to provide a method for producing particles in which aluminum is contained throughout the entire surface. [Means for solving the problem]

[0008] The present invention provides a method for producing aluminum-containing particles, A mixture of treated particles containing heavy metals with a specific gravity of 4 or higher, an aluminum source, an activator containing a halide, and a sintering inhibitor is obtained by mixing them together. The mixed particles are heated, and the gaps between the sintering inhibitors formed by the sintering inhibitors are used to calorify the particles to be treated, thereby obtaining a treated mixture containing aluminum-impregnated particles. A method is provided for removing the sintering inhibitor from the treated mixture and recovering the aluminum-impregnated particles. [Effects of the Invention]

[0009] The present invention provides a method for producing particles in which aluminum has permeated throughout the entire surface. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram schematically shows an example of a flow chart for a particle manufacturing method according to one embodiment of the present invention. [Figure 2] This diagram schematically shows how the mixed particles are packed into the reaction vessel. [Figure 3] This figure shows a cross-section of a spherical particle obtained in one embodiment of the present invention ((a)) and the distribution of aluminum contained in the cross-section ((b)). [Figure 4] This figure shows a cross-section of spherical particles obtained in another embodiment of the present invention ((a)) and the distribution of aluminum contained in the cross-section ((b)). [Figure 5] This figure shows a cross-section of spherical particles obtained in yet another embodiment of the present invention ((a)) and the distribution of aluminum contained in the cross-section ((b)). [Figure 6] This figure shows a cross-section of spherical particles obtained in yet another embodiment of the present invention ((a)) and the distribution of aluminum contained in the cross-section ((b)). [Figure 7]Figure showing the cross-section of spherical particles ((a)) obtained in yet another embodiment of the present invention, and the distribution of aluminum ((b)) contained in the cross-section. [Figure 8] Figure showing the cross-section of spherical particles ((a)) obtained in yet another embodiment of the present invention, and the distribution of aluminum ((b)) contained in the cross-section. [Figure 9] Figure showing the cross-section of spherical particles ((a)) obtained in yet another embodiment of the present invention, and the distribution of aluminum ((b)) contained in the cross-section.

Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment of the present invention will be described.

[0012] As described above, on the surface of the particles in Reference Document 1, there may be regions where aluminum does not exist. In the case of particles including such surface regions where aluminum does not exist, there may be cases where the desired characteristics cannot be exhibited.

[0013] As a method for dealing with the problem of lack of aluminum on such a surface, it is conceivable to perform a calorizing treatment on the particles to be treated.

[0014] The calorizing treatment is a technique for diffusing and infiltrating aluminum at high temperature on the surface of a plate-shaped or block-shaped object to be treated. For example, when the object to be treated contains iron, a uniform iron-aluminum alloy can be formed on the surface of the object to be treated after the calorizing treatment.

[0015] However, when the calorizing treatment is applied to an object to be treated containing a small amount of oxygen, reduction of oxides in the object to be treated and oxidation of aluminum occur, and a solid-phase contact reaction (thermite reaction) accompanied by large heat generation occurs. When the thermite reaction occurs, due to heat, the reaction progresses rapidly, so there is no time for the heat to dissipate to the outside, and as a result of heat accumulation, the reaction system reaches a high temperature of several thousand degrees Celsius.

[0016] Therefore, when the material to be treated is in particulate form, the thermite reaction occurs, causing the treatment environment to become extremely hot, and the resulting mixture (hereinafter referred to as the "treated mixture") becomes a solid mass in which all the particles are firmly bonded together.

[0017] Furthermore, once such a lumpy processed mixture is formed, it becomes impossible to separate the sintering inhibitor from the processed mixture. Consequently, there is a problem in that it becomes impossible to recover the calorified particles (hereinafter also referred to as "aluminum-impregnated particles") from the processed mixture.

[0018] In contrast, in one embodiment of the present invention, A method for producing aluminum-containing particles, A mixture of treated particles containing heavy metals with a specific gravity of 4 or higher, an aluminum source, an activator containing a halide, and a sintering inhibitor is obtained by mixing them together. The mixed particles are heated, and the gaps between the sintering inhibitors formed by the sintering inhibitors are used to calorify the particles to be treated, thereby obtaining a treated mixture containing aluminum-impregnated particles. A method is provided for removing the sintering inhibitor from the treated mixture and recovering the aluminum-impregnated particles.

[0019] Here, "heavy metals with a specific gravity of 4 or higher" include iron, chromium, nickel, molybdenum, bismuth, tungsten, cobalt, zirconium, manganese, and copper, among others.

[0020] Furthermore, the "particles to be treated" are not limited to single metals, but may also be alloys containing the above elements.

[0021] In one embodiment of the present invention, a calorizing treatment is used to impregnate the particles to be treated with aluminum. In another embodiment of the present invention, a calorizing treatment is performed using the gaps formed between the anti-sintering agents.

[0022] Due to these characteristics, the method according to one embodiment of the present invention significantly reduces the possibility of the treated particles adhering to the anti-sintering agent and / or other treated particles, even if a thermite reaction occurs in the reaction system. This is because the aforementioned gaps serve to provide numerous "small compartments" for the reactions that are separated from each other.

[0023] As a result, the treated mixture produced after calorizing is not in a mass-aggregated form, but rather the aluminum-impregnated particles and the sintering inhibitor are separated from each other. Therefore, in the method according to one embodiment of the present invention, the sintering inhibitor can be removed from the treated mixture relatively easily after calorizing. Furthermore, this allows for the relatively easy separation and recovery of the aluminum-impregnated particles.

[0024] Thus, the method according to one embodiment of the present invention makes it possible to properly perform calorification on the particles to be treated, and to properly produce particles in which aluminum is contained throughout the entire surface.

[0025] (Method for producing particles according to one embodiment of the present invention) Next, with reference to the drawings, a method for producing particles according to one embodiment of the present invention will be described.

[0026] Figure 1 schematically shows an example of a flow chart of a particle manufacturing method according to one embodiment of the present invention.

[0027] As shown in Figure 1, a method for producing particles according to one embodiment of the present invention (hereinafter referred to as the "first method") is: A step (S110) to prepare mixed particles containing the particles to be treated, an aluminum source, an activator, and an anti-sintering agent, The process involves heating the mixed particles to calorify the particles to be treated (S120), The process of removing the sintering inhibitor (S130), It holds.

[0028] The following provides a more detailed explanation of each step.

[0029] (Step S110) First, the mixed particles are prepared.

[0030] The mixed particles include the particles to be treated, an aluminum source, an activator, and a sintering inhibitor. Each of these particles is described below.

[0031] (Particles to be treated) As mentioned above, the particles to be treated contain heavy metals with a specific gravity of 4 or higher. The heavy metals may include, for example, at least one element selected from iron, chromium, nickel, molybdenum, bismuth, tungsten, cobalt, zirconium, manganese, and copper.

[0032] Furthermore, the particles to be treated are not limited to single metals, but may also be alloys containing the above elements. For example, the particles to be treated may be stainless steel particles or iron-aluminum alloy particles.

[0033] Furthermore, the particles to be treated may contain unavoidable impurities in addition to heavy metals with a specific gravity of 4 or higher. Examples of unavoidable impurities include phosphorus, sulfur, and carbon.

[0034] For clarity, the following explanation will describe the first manufacturing method using the example of iron (containing unavoidable impurities) as the particles to be treated. In this case, unavoidable impurities include manganese, phosphorus, sulfur, and carbon.

[0035] The average particle size of the particles to be treated is selected to be smaller than the average particle size of the sintering inhibitor, as described later. For example, the maximum particle size of the particles to be treated may be 0.29 times or less the average particle size of the sintering inhibitor.

[0036] The particle size of the particles to be treated may be, for example, in the range of 10 μm to 600 μm.

[0037] In this application, "average particle size" refers to the measurement method specified in JIS Z 8801.

[0038] Specifically, several sieves with different mesh sizes are stacked in order from the smallest to the largest, and the particles to be measured are vibrated at a constant amplitude for a certain period of time to separate the particles. Next, the mass of the particles remaining on each sieve is measured, and the particle size distribution of the particle mass is graphed. The particle size corresponding to 50% of the cumulative value of the obtained particle size distribution is defined as the "average particle size."

[0039] However, the particle size of the particles to be treated is expressed as a range between the minimum and maximum values.

[0040] (Aluminum source) The aluminum source may be aluminum metal particles or aluminum alloy particles.

[0041] The average particle size of the aluminum source is selected to be smaller than the average particle size of the sintering inhibitor. For example, the average particle size of the aluminum source may be 0.29 times or less the average particle size of the sintering inhibitor.

[0042] The average particle size of the aluminum source may be, for example, in the range of 10 μm to 600 μm.

[0043] Furthermore, it is preferable that the average particle size of the aluminum source be smaller than the average particle size of the particles to be treated.

[0044] (Activating agent) The activator plays a role in promoting the calorification process of the particles to be treated by forming a vapor of metal halide.

[0045] The activator includes, for example, at least one of ammonium chloride, iron chloride, aluminum chloride, iron fluoride, and aluminum fluoride. The activator is added, for example, in an amount ranging from 0.1% to 2% by mass relative to the total mixed particles.

[0046] (Sintering inhibitor) The anti-sintering agent may contain at least one of alumina, kaolin, and silicon dioxide.

[0047] The sintering inhibitor may have at least one shape selected from the group consisting of, for example, spherical, triangular pyramidal, triangular prismatic, tetrahedral, conical, and cylindrical shapes.

[0048] Furthermore, the anti-sintering agent has a sufficiently large average particle size compared to the particles to be treated and the aluminum source. For example, the average particle size of the anti-sintering agent is selected to be at least 3.4 times the maximum particle size of the particles to be treated and the average particle size of the aluminum source.

[0049] The average particle size of the sintering inhibitor may be in the range of, for example, 500 μm to 5000 μm.

[0050] (mixed particles) Mixed particles are prepared by mixing the above components.

[0051] The amount of treated particles in the total mixed particles is, for example, in the range of 10% to 40% by mass. The amount of aluminum source in the total mixed particles is, for example, in the range of 2% to 20% by mass. The amount of sintering inhibitor in the total mixed particles is, for example, in the range of 40% to 80% by mass.

[0052] (Process S120) Next, the mixed particles prepared in step S110 are heat-treated. For this reason, the mixed particles may be packed into the reaction vessel.

[0053] By heating the reaction vessel, the particles to be treated undergo calorification. That is, aluminum generated from the aluminum source diffuses and penetrates into the particles to be treated, forming aluminum-permeated particles.

[0054] Here, the greater the difference in ionization tendency between the agent to be treated in the mixed particles and the aluminum source, the more heat will be generated by the thermite reaction between the mixed particles when the reaction vessel is heated. This is because the aluminum reacts with the trace amounts of oxygen contained in the particles to be treated, reducing them.

[0055] When such a thermite reaction occurs, the reaction vessel becomes extremely hot, and the resulting mixture, or "treated mixture," takes on a lumpy form in which all the particles are firmly bound together. Furthermore, once such a lumpy treated mixture is formed, a problem may arise in that it becomes impossible to separate the sintering inhibitor from the treated mixture afterward.

[0056] In contrast, the first manufacturing method can significantly suppress the formation of lumpy mixtures.

[0057] The following explanation of this feature will be given with reference to Figure 2.

[0058] Figure 2 schematically shows an example of the configuration when the mixed particles are filled into a reaction vessel. As shown in Figure 2, the reaction vessel is filled with the components of the mixed particles: the particles to be treated 352, the aluminum source 354, the activator, and the sintering inhibitor 358.

[0059] Note that the activator is omitted in Figure 2. Also, it is assumed here that each component of the mixed particles is spherical.

[0060] Here, the diameter of the sintering inhibitor 358 (φ S (represented by) the diameter (φ) of the particles to be processed 352. Fe (represented by) and the diameter (φ) of the aluminum source 354 Al If the amount is sufficiently large compared to the amount shown, a void 365 is created between adjacent sintering inhibitors 358. The treated particles 352 and the aluminum source 354 are then placed in the void 365 created by the sintering inhibitor 358.

[0061] When the reaction vessel is heated with the mixed particles arranged in this manner, even if a thermite reaction occurs within the reaction vessel, the likelihood of the treated particles 352 adhering to the sintering inhibitor 358 and / or other treated particles 352 can be greatly reduced. This is because the voids 365 serve to provide numerous reaction "small compartments" for the calorizing process.

[0062] As a result, the processed mixture formed after the heat treatment is not in the form of a lump-like agglomeration as a whole, but the aluminum infiltration particles and the sintering inhibitor 358 are in a mutually separated state. Therefore, in the subsequent process, it becomes possible to recover the aluminum infiltration particles from the processed mixture.

[0063] Table 1 below shows examples of the filling of mixed particles capable of expressing the above effects.

[0064] Here, the particles to be processed 352 are assumed to be spherical iron particles (density 7.87 g / cm 3 ), the aluminum source 354 is assumed to be spherical aluminum particles (density 2.70 g / cm 3 ), the activator is assumed to be spherical ammonium chloride particles (density 1.527 g / cm 3 ), and the sintering inhibitor 358 is assumed to be spherical alumina (density 4.00 g / cm 3 ).

[0065] Also, assuming that the average particle diameter φ S of the sintering inhibitor 358 is 1000 μm, the particle diameter φ Fe of the particles to be processed 352 is 38 μm to 75 μm, the average particle diameter φ Al of the aluminum source 354 is 50 μm, and the average particle diameter of the activator is assumed to be 10 μm.

[0066]

Table 1

[0067] Assuming that the entire void 365 (100%) is filled with the particles to be processed 352, the aluminum source 354, and the activator, as an example, the amount of the particles to be processed 352 is 2.216 kg, the amount of the aluminum source 354 is 1.491 kg, and the amount of the activator is 0.067 kg.

[0068] Similarly, if 85% of the void 365 is filled with treated particles 352, aluminum source 354, and activator, the amount of treated particles 352 can be calculated as 1.879 kg, the amount of aluminum source 354 as 1.253 kg, and the amount of activator as 0.066 kg.

[0069] In the above calculations, the Al / Fe ratio in the mixed particles is assumed to be 40 / 60 (by mass). Furthermore, the amount of activator is assumed to be 0.5 wt% of the total.

[0070] Even when the sintering inhibitor 358 is filled in a manner other than close-packed, the amounts of each component can be calculated in the same way.

[0071] Furthermore, if the sintering inhibitor 358 is spherical, in order to obtain the aforementioned effects, it is preferable that the filling rate of the sintering inhibitor 358 be in the range of 55% to 74% (when closely packed).

[0072] Furthermore, the packing rate of the treated particles 352, aluminum source 354, and activator in the voids 365 created by the sintering inhibitor 358 is preferably in the range of 60% to 100%.

[0073] However, in practice, the sintering inhibitor 358 may be non-spherical, so a suitable range for the filling rate of the sintering inhibitor 358 is assumed to be 50% to 80%.

[0074] Thus, in the first manufacturing method, the voids 365 that form between the sintering inhibitors 358 can be used to perform the calorification treatment on the particles 352 to be treated.

[0075] The treatment atmosphere for calorizing can be any inert atmosphere that does not contain oxygen, such as an argon gas atmosphere.

[0076] The processing temperature is not particularly limited, as long as aluminum diffusion and penetration occur within the particles being processed. The processing temperature may be, for example, in the range of 800°C to 1100°C.

[0077] There are no specific limitations on processing time, but it is typically in the range of 1 to 10 hours.

[0078] (Step S130) Next, the sintering inhibitor is removed from the powdered treated mixture formed in step S120. The sintering inhibitor may be removed, for example, by sieving the treated mixture using a sieve that allows only particles with a small average particle size to pass through.

[0079] As mentioned above, the first manufacturing method can significantly suppress the temperature increase of the reaction system due to the accumulation of excess heat that may occur in the thermite reaction.

[0080] Therefore, in the first manufacturing method, the sintering inhibitor and the aluminum impregnated particles can be separated relatively easily.

[0081] Through the above process, the first manufacturing method can properly produce particles in which aluminum is contained throughout the entire surface. [Examples]

[0082] The following describes examples of the present invention. In the following description, Examples 1 to 7 are examples, and Example 11 is a comparative example.

[0083] (Example 1) Calorified iron particles were prepared using the following method.

[0084] First, a mixed particle was prepared by thoroughly mixing iron particles (10.96% by mass) as the particles to be treated, aluminum particles (10.96% by mass) as the aluminum source, ammonium chloride particles (0.50% by mass) as the activator, and spherical alumina particles (77.58% by mass) as the anti-sintering agent.

[0085] The iron particles had a particle size of 38 μm to 75 μm, the aluminum particles had an average particle size of 50 μm, the activator had a particle size of 10 μm, and the alumina particles had a particle size of 1000 μm.

[0086] This mixed particle was packed into a heat-resistant container. Calculations showed that the alumina particles filled 74% of the container. Iron particles, aluminum particles, and ammonium chloride particles were then packed to occupy 85% of the remaining 26% of the void.

[0087] Next, the atmosphere inside the heat-resistant container was replaced with an argon atmosphere, and then the heat-resistant container was heated to 1000°C. After being held at 1000°C for 10 hours, the heat-resistant container was furnace-cooled.

[0088] Subsequently, the treated mixture was removed from the heat-resistant container and passed through a #32 mesh sieve to remove the alumina powder. This yielded spherical particles (hereinafter referred to as "particles according to Example 1").

[0089] (Example 2) Using the same method as in Example 1, calorified iron particles (hereinafter referred to as "particles related to Example 2") were prepared.

[0090] However, in this Example 2, the iron particle content in the mixed particles was set to 13.20% by mass, the aluminum particle content to 9.96% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 76.34% by mass.

[0091] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0092] (Example 3) Using the same method as in Example 1, calorified iron particles (hereinafter referred to as "particles related to Example 3") were prepared.

[0093] However, in this Example 3, the iron particle content in the mixed particles was set to 14.24% by mass, the aluminum particle content to 9.49% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 75.77% by mass.

[0094] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0095] (Example 4) Using the same method as in Example 1, calorified iron particles (hereinafter referred to as "particles related to Example 4") were prepared.

[0096] However, in this Example 4, the iron particle content in the mixed particles was set to 15.71% by mass, the aluminum particle content to 8.83% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 74.96% by mass.

[0097] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0098] (Example 5) Calorized iron particles (hereinafter referred to as "particles related to Example 5") were prepared using the same method as in Example 1.

[0099] However, in this Example 5, the iron particle content in the mixed particles was set to 16.87% by mass, the aluminum particle content to 8.31% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 74.32% by mass.

[0100] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0101] (Example 6) Calorized iron particles (hereinafter referred to as "particles related to Example 6") were prepared using the same method as in Example 1.

[0102] However, in this example 6, the iron particle content in the mixed particles was set to 17.69% by mass, the aluminum particle content to 7.95% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 73.87% by mass.

[0103] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0104] (Example 7) Calorized iron particles (hereinafter referred to as "particles related to Example 7") were prepared using the same method as in Example 1.

[0105] However, in this example 7, the iron particle content in the mixed particles was set to 22.74% by mass, the aluminum particle content to 5.68% by mass, the ammonium chloride particle content as an activator to 0.5% by mass, and the spherical alumina particle content as an anti-sintering agent to 71.08% by mass.

[0106] Other conditions, such as the packing density of alumina particles, are the same as in Example 1.

[0107] (Example 11) We attempted to produce calorified iron particles using the same method as in Example 1.

[0108] However, in this example 11, the average particle size of the iron particles in the mixed particles was set to 50 μm, the average particle size of the aluminum particles to 50 μm, and the average particle size of the alumina particles to 60 μm. In addition, the content of iron particles in the mixed particles was set to 56.00 mass%, the content of aluminum particles to 24.00 mass%, the content of ammonium chloride particles as an activator to 0.50 mass%, and the content of alumina particles to 19.50 mass%.

[0109] The heating temperature was set to 1000°C, and the heating time was set to 10 hours.

[0110] The treated mixture obtained after heat treatment was lumpy, and it was difficult to separate and remove the alumina particles.

[0111] Table 2 below summarizes the content and particle size of each component in the mixed particles used in each example.

[0112] [Table 2] Furthermore, Table 3 below summarizes the packing density of alumina particles and the packing density of other components in the voids for each example.

[0113] [Table 3] In Example 11, the particle size of the alumina particles is approximately the same as that of the other components, so the packing density is omitted.

[0114] (evaluation) Morphological observations were performed using the particles from each example.

[0115] (Cross-sectional analysis) Using the particles from each example, samples for cross-sectional observation were prepared using the following method.

[0116] First, multiple particles were embedded in resin, and the resin was allowed to harden. Next, the resin was polished using abrasive paper and a buffing device to expose the cross-sections of the particles.

[0117] The objects of observation were spherical particles having a "maximum cross-section." Here, "maximum cross-section" refers to the cross-section passing through the center of the spherical particle. Therefore, the "maximum cross-section" of a particle has substantially the same dimensions as the diameter of the particle.

[0118] In the following examples 1 to 7, the spherical particles to be observed will be referred to as "Sample 1" to "Sample 7," respectively.

[0119] In samples 1 through 7, the cross-sections of spherical particles were observed using a scanning electron microscope (SEM). The amounts of iron and aluminum contained in the cross-sections of the spherical particles were also evaluated by EDX analysis.

[0120] Figures 3 to 9 show the cross-section of the spherical particles obtained in each sample ((a)) and the distribution of aluminum contained in the cross-section ((b)).

[0121] For example, Figure 3 shows a cross-section of the spherical particles obtained in Sample 1 (Figure 3(a)) and the distribution of aluminum contained in the cross-section (Figure 3(b)). Similarly, Figure 4 shows a cross-section of the spherical particles obtained in Sample 2 (Figure 4(a)) and the distribution of aluminum contained in the cross-section (Figure 4(b)), and so on.

[0122] Furthermore, in each sample, the distribution of iron in the cross-section was inverted from the distribution of aluminum.

[0123] Figures 3 to 9 show that in all of samples 1 to 7, the surface of the particles is impregnated with aluminum throughout.

[0124] Next, energy-dispersive X-ray (EDX) analysis was performed on the cross-sections obtained from each sample to evaluate the concentrations of aluminum and iron contained throughout the entire particle cross-section.

[0125] Table 4 below summarizes the analysis results obtained for each sample.

[0126] [Table 4] These results indicate that in each sample, the amount of aluminum contained in the particles was approximately equal to the amount of aluminum contained in the mixed particles.

[0127] This application claims priority based on Japanese Patent Application No. 2020-202260, filed on 4 December 2020, and the entire contents of the said Japanese application are incorporated herein by reference. [Explanation of Symbols]

[0128] 352 Particles to be treated 354 Aluminum source 358 Sintering inhibitor 365 void

Claims

1. A method for producing aluminum-containing particles, A mixture of treated particles containing heavy metals with a specific gravity of 4 or higher, an aluminum source, an activator containing a halide, and a sintering inhibitor is obtained by mixing them together. The treated particles and the aluminum source are placed in the gaps that form between adjacent sintering inhibitors. The mixed particles are heated, and the gaps are used as separate reaction compartments to calorify the particles to be treated, obtaining a treated mixture containing aluminum-impregnated particles; the sintering inhibitor is removed from the treated mixture to recover the aluminum-impregnated particles; The average particle size of the treated particles is smaller than the average particle size of the sintering inhibitor. A method wherein the average particle size of the aluminum source is smaller than the average particle size of the sintering inhibitor.

2. The mixed particles are filled into the reaction vessel, The method according to claim 1, wherein the filling rate of the sintering inhibitor relative to the volume of the reaction vessel is in the range of 50% to 80%.

3. The method according to claim 1 or 2, wherein the anti-sintering agent has at least one shape selected from the group consisting of spherical, triangular pyramidal, triangular prismatic, tetrahedral, conical, and cylindrical shapes.

4. The method according to any one of claims 1 to 3, wherein the anti-sintering agent comprises at least one of alumina, kaolin, and silicon oxide.

5. The method according to any one of claims 1 to 4, wherein the maximum particle size of the treated particles is 0.29 times or less the average particle size of the sintering inhibitor.

6. The method according to any one of claims 1 to 5, wherein the average particle size of the aluminum source is 0.29 times or less the average particle size of the sintering inhibitor.

7. The method according to any one of claims 1 to 6, wherein the particle size of the treated particles is in the range of 10 μm to 600 μm.

8. The method according to any one of claims 1 to 7, wherein the average particle size of the anti-sintering agent is in the range of 500 μm to 5000 μm.

9. The method according to any one of claims 1 to 8, wherein the heavy metal comprises at least one selected from the group consisting of iron, chromium, nickel, molybdenum, bismuth, tungsten, cobalt, zirconium, manganese, and copper.

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